The invention is concerned with disposable diapers that have refastenable adhesive closures and is specifically concerned with disposable diapers that are fastened by a two point closure system.
U.S. Pat. No. 4,699,622 (Toussant et al.) observes: "In general, disposable diapers all have the same basic structure which comprises an absorbent core encased between a liquid permeable user contacting topsheet and a liquid impermeable backsheet" (col. 1, lines 21-24). The diaper illustrated in the Toussant et al patent has an outer fastening means 54 bearing a pressure-sensitive adhesive layer that is adhered to the front of the diaper to encircle the wearer's waist. Almost every disposable diaper now on the market has such an outer fastening means consisting of two pressure-sensitive adhesive tapes at each ear of the back of the diaper as shown in FIGS. 1 and 3 of U.S. Pat. No. 3,848,594 (Buell). One of these tapes is a pressure-sensitive adhesive fastening tab which is initially protected by being folded over onto another tape, a release tape, from which it is peeled off by a "grip tab 48" to be in a position to adhere to the front of the diaper.
Although not shown in either the Toussant et al or the Buell patent, many disposable diapers have a third adhesive tape, namely a frontal tape which is contacted by the fastening tape.
The Toussant et al patent concerns the problem that disposable diapers tend to loosen due to the combined effects of forces generated by elasticized leg opening and movements of the diaper wearer. Its answer to this problem is to employ in addition to a conventional outer fastening means (54), as discussed above, an inner fastening means (60), such as a layer of adhesive applied to panels 62 that are "portions of the second waist portion 44 (the front of the diaper) which are overlain by the first waist portion 42 (the back of the diaper) when the diaper is fastened about the waist of the wearer" (col. 8, lines 48-51).